The invention relates to fuel injectors, and more particularly, to fuel injectors having multiple interchangeable nozzle plates.
Fuel injectors are commonly employed in internal combustion engines to provide precise metering of fuel into each combustion chamber. Additionally, each fuel injector atomizes the fuel during injection into the respective combustion chamber, breaking the fuel into a large number of very small particles, increasing the surface area of the fuel being injected and allowing the oxidizer, typically ambient air, to more thoroughly mix with the fuel prior to combustion. The precise metering and atomization of the fuel reduces combustion emissions and increases the fuel efficiency of the engine.
An electromagnetic fuel injector typically utilizes a solenoid assembly to supply an actuating force to a fuel metering valve. Typically, the fuel metering valve is a plunger style needle valve which reciprocates between a closed position, when the needle is seated in a seat to prevent fuel from escaping through a metering orifice into the combustion chamber, and an open position, where the needle is lifted from the seat, allowing fuel to discharge through the metering orifice and into the combustion chamber.
Typically, fuel injectors employ a metering nozzle or orifice comprised of a single orifice plate with a plurality of orifice openings extending therethrough through which pressurized fuel is introduced into the combustion chamber. Modifications to these metering orifices include multiple orifice plates stacked upon each other to provide alternate pathways for the fuel immediately prior to injection into the combustion chamber. These alternate pathways increase the turbulence of the fuel flow, providing greater atomization of the fuel as the fuel passes through the orifice openings, providing for enhanced mixture of the fuel with combustion air which reduces unwanted exhaust emissions and improves the fuel efficiency of the engine.
Typically, injectors with multiple orifice plates include a first top orifice plate having a plurality of openings extending therethrough, a bottom orifice plate having a like plurality of openings extending therethrough, and an open space between the top orifice plate and the bottom orifice plate for redirecting the fuel flow between the outlet of the top orifice plate orifice openings and the inlet of the bottom orifice plate orifice openings. Additionally, the space between the top and bottom orifice plates generally includes walls or other obstructions which tend to direct the fuel from the outlet of the top orifice plate to a particular orifice opening in the bottom orifice plate, creating a relatively laminar flow and precluding a fuel stream from one top orifice plate orifice opening from impinging into the stream from another top orifice plate orifice opening. Additionally, fuel injectors with multiple orifice plates require the orifice plates to be fused or electroplated together, precluding the ability to interchange orifice plates to obtain different fuel flow patterns.
It would be beneficial to develop a fuel injector having a metering orifice with multiple orifice plates which includes a fully open space between top and bottom orifice plates and which also allows interchangeability of different orifice plates to produce different flow stream patterns.
Briefly, the present invention provides a fuel injector comprising a housing, a seat, a needle, and a multi-layer orifice plate assembly. The housing has an inlet, an outlet and a longitudinal axis extending therethrough. The seat is disposed proximate the outlet and includes a sealing surface and a passage extending therethrough. The needle is reciprocally located within the housing along the longitudinal axis between a first position wherein the needle is displaced from the seat, allowing fuel flow past the needle, and a second position wherein the needle is biased against the seat, precluding fuel flow past the needle. The multi-layer orifice plate assembly is located at the housing outlet. The orifice plate assembly includes a first orifice plate having a plurality of first openings extending therethrough. The orifice plate assembly also includes a second orifice plate having a plurality of second openings extending therethrough. The plurality of first openings and the plurality of second openings are fluidly connected by at least one channel.
The present invention also provides a fuel injector comprising a housing, a seat, a needle and a multi-layer orifice plate assembly. The housing has an inlet, an outlet and a longitudinal axis extending therethrough. The seat is disposed proximate the outlet and includes a sealing surface and a passage extending therethrough. The needle is reciprocally located within the housing along the longitudinal axis between a first position wherein the needle is displaced from the seat, allowing fuel flow past the needle, and a second position wherein the needle is biased against the seat, precluding fuel flow past the needle. The multi-layer orifice plate assembly is located at the housing outlet and includes a first orifice plate having a plurality of first openings extending therethrough. The plurality of first openings are each spaced a first predetermined radial distance from the longitudinal axis. The orifice plate assembly further includes a second orifice plate having a plurality of second openings extending therethrough. The plurality of second openings are each spaced a second predetermined radial distance from the longitudinal axis such that the second predetermined radial distance is less than the first predetermined radial distance. The orifice plate assembly further includes a third orifice plate located between the first orifice plate and the second orifice plate. The third orifice plate includes a third orifice plate central opening extending therethrough along the longitudinal axis such that the third orifice plate central opening fluidly connects the plurality of first orifice plate openings and the plurality of second orifice plate openings.
The present invention also provides a method of accelerating a velocity of fuel through a fuel injector having a longitudinal axis and a multi-layer orifice plate. The method comprises the steps of directing the fuel through openings in a top orifice plate; directing the fuel into a space between the top orifice plate and a bottom orifice plate; and directing the fuel through openings in the bottom orifice plate, the openings in the bottom orifice plate being radially closer to the longitudinal axis than the openings in the top orifice plate.